Grinding machine



Dec. 20, 1938. F. s. HAAS ET AL 2,141,065.

' @BINDING MACINE Filed June 1, 1957 5 sheds-sheet 1 ATTORNEY.

Dec. 2o, 1938. 4F. s'. HAAS ET AL 2,141,065

GRINDING MACHINE Filed June l, 1957 5 Sheets-Sheet 2 Dec. 20, 1938. F. s. HAAS E T AL 2,141,065 GRINDING MACHINE Filed June l, 1937 5 Sheets-Sheet 3 Ila 57 Dea 20, 1938. Fl s, HAAS ET AL 2,141,065

GRINDING MACHINE Filed June l, 1937 5 Sheets-Sheet 4 ATTORNEY.

2o, 193s. F. s. HMS ET AL 2,141,065

GRINDING MACHINE Filed June 1, 1937 5 Sheets-Sheet 5 A f fff L 1 V10 d K n ATTORNEY.

Patented Dec. 20,

UNITED STATES l PATENT OFFICE nati,

Ohio, assignors to Cincinnati Grinders Incorporated, Cincinnati, Ohio, a. corporation of Ohio Application .inne 1, 1937, serial No. 145,729

15 claims.

j o This invention relates to improvements in `grinding machinery and has particular reference to an improved mechanism for controlling the cycle of operation of. the several shiftable parts of the machine.

' One of the principal objects of the present invention is the provision of an improved control mechanism for insuring proper sequential work positioning and performance of the grinding operation.

A further object of the present invention is the provision of a combined hydro-electrical control mechanism for controlling the positioning of the work within the grinding machine, the performance ofthe grinding operation and the subsequent removalof work from the grinding position preparatory to substitution of the new piece to be machined.

An additional object of the present invention is the provision in connection with a machine of the centerless type of novel mechanism for insuring proper positioning and prerotation, Darticularly in'conjunction with extremely large and heavy work pieces prior to the inception of the grinding operation.

An additional object is the provision in connection with a multiple grinding wheel centerless grinder having independent wheel head adjustments of an improved automatic control mechanism for determining the positioning and rotation ,of the Work which will insure maintenance of the work in proper grinding position until all ofthe grinding wheels have completed their respective functions.

A further object of the invention is the. provision of an improved work rotating mechanism and control therefor, particularly adapted for use in driving large work pieces while supported within the throat of a centerless grinder.

Other objects and advantages vof the present invention should be readily apparent byv reference to the following speciiication, considered in conjunction with the accompanying drawings forming a part thereof and it is to be understood that we may make any modifications in thespecific structural details hereinafter disclosedl with- Figure 2 is a plan view thereof.

Figure 3 is a sectional 'view as on the4 line 3--3 of Figure 2.

Figure 4 is a view partly in elevation and partly in section on the line 4 4 of certain of the work supporting and controlling mechanism as viewed from the left of Figure 3.

"Figure 5 is a longitudinal sectional view through the work driving mechanism as on the y line 5-5 of Figure 2.

Figure 6 is a fragmentary sectional view of the work rest blade. i Figure 'l is a fragmentary sectional view of the rack and pinion actuator for the elevating mechanism.

Figure 8 is a sectional view illustrating the infeed controlling cam and associated controls.

Figure 9 is a diagrammatic view of the hydraulic controls for the work elevating and rotating mechanisms illustrating the position occupied by the parts when in work clamping position.

Figure l0 is a diagrammatic view 'illustrating the position of the control valves for the work driver when the latter is in released or inoper-4 ative position.

Figure 11 is a diagrammatic ,view of the essential portion of the electrical controls of the machine as respects the present invention.

In the drawings in which similar characters of reference are employed to denote corresponding parts throughout the several views:

The numeral I5 designates the main base or bed of the-machine, preferably imbedded in a suitable concrete or like foundation I6. By reference particularly yto Figures 2 and 4 of the drawings it will be noted that the present machine is particularly designed for grinding cylindrical surfaces on portions of quite large work pieces, vas for example, the complete rear axle housing of a motor vehicle or the like. It will, therefore, be understood that the parts in question and to be controlled are quite massive and present problems not existing with ordinary centerlessgrinders designed for operation upon relatively small or easily handled parts.

Mounted on the bed I5 is a slide I1 carrying the regulating wheel I8 for engagement with one of the cylindrical portions I9 of the work piece. It is to bevunderstood that two such portionsIS are simultaneously ground-and that the regulating wheel units, except for their right and left hand type, are substantially duplicates one of the other, said wheels being rotated as by motors located at 20. The regulating-wheel slides are individually adjustable as by the pilot wheels 2i and adjusting screws 22 for general positioning purposes.

Mounted on the base I5 in opposition to each regulating wheel unit is a grinding wheel unit including a slide 23 movable toward and from its opposed regulating wheel I8 to compensate for wear or variation in size of the grinding wheel. This slide is provided with a trunnion at 24 about which the base 25 is oscillatable. This base supports in eccentric relation to the trunnion the spindle 26 for the grinding wheel 21, these axes being so related that tilting of the base 25 about the trunnion axis 26 will cause in and out movement of the periphery of the grinding wheel with respect to the regulating wheel and thus to the portion I9 of the work disposed therebetween. The motor at 28 on the base 25 oscillatable with the grinding wheel, serves to effect rotation thereof at prescribed grinding speed.

Supported on the bed I5 is a pair of work rest brackets 29, as particularly illustrated in Figures 4 and 6. Each of these brackets is provided with a slot as at 30 to receive the work rest blade 3| having the inset rollers 32 for supporting the portion of work to be ground as is particularly indicated in Figures 3 and 4. The blades 30 are formed with passages as at 32 to receive the plungers 33, while threaded into the upper portion of these passages are the adjusting bolts 34 coacting with the plungers for accurate adjustments of the blades and work supporting rollers, set screws 35 being provided for locking the blades in their adjusted position. By reference to Figure 6 it will be noted that the supporting rollers are offset with respect to the work axis in the direction of the grinding wheel so that gravity will tend to force the work toward the regulating wheel in order that the same may properly frictionally engage and effect rotation of the work piece.

Work elevating mechanism Due to the size of the work piece involved they are ordinarily shifted to the machine by a crane or like device, but must then be smoothly placed in position on the work rest blade to avoid springing of the parts of the machine or chipping of the wheel. To effect this result, there are provided rising from the base I5, or its auxiliary regulating Wheel supporting section 36, guides 31 for the vertically movable posts 38 to which are pinned the tubular sleeves 39 having at their upper ends the Vs or notches 4D for engagement with the work piece. Suitably telescoping shield members 4| are contained between the posts and sleeves to protect the post bearings from grit and coolant during the adjusting movement of the parts. As shown, the posts are provided at their lower ends with the rack portions 42 meshing with the pinions 43 on the actuating shaft 44.

One of these pinions is provided with a second reduced pinion portion 45 engaged by rack 46 on slide rod 41 to piston 48 operating in cylinder 49. By reference particularly to .Figure 3 it will be noted that this piston cylinder mechanism is of the diiferential type, further that pressure against the right hand end of the piston will operate through the rack and pinion mechanism thus described to elevate the sleeves 39 and thus the work piece 58. Similarly, release of pressure against the right hand end will, either by gravity or through weight of the parts cause downward movement of the sleeves 39 until the Work is deposited on the rollers 32. There is preferably at least sufficient pressureexerted against piston 48 to' retract the notched portions of the members 39 away from the work as indicated in Figure 3.

In order that the work may be not only gravitalating wheel, there have been provided the vertically adjustable brackets 5| secured as by bolts 52 to the face of the base portion 36. These brackets bear trunnions 53 on which are pivoted the arms 54 having at their upper ends rollers 55 for engagement with the work piece. At their lower ends these arms are provided with the resilient plunger devices 56 for springing the arms outward about the pivots 53 as respects the lower end of the arms so that the rollers 55 will be moved inwardly. Adjusting stopping devices 51 serve to determine the amount of this inward swinging movement;

It will be noted that the slides 39- are provided with the cam plates 58 having beveled terminal portions 59 and 60 for engagement with the release controlling rollers 6| on the arm 54. By reference to Figure 3 it will be noted that when 'the members 39 are in depressed position that the cams have then moved entirely out of engagement with the rollers. However, as theelevating fixture starts to rise, the portion 59 will engage the adiacent roller 6|., camming the arm outwardly about its pivot in a position such that the rollers 55 tend to disengage the work piece prior to its elevating movement by the fixture. Similarly, if the extent of upward movement be considerable, the rollers 6| may again ride down on the portion 60 of the cams so that the members 55 are swung inward toward the regulating wheel to the extent limited by stop 51, the rollers having been reversely swung by interengagementy of the parts 69 and 6| as the fixture descends bearing the fresh piece to be machined.

It is to be understood that in the grinding of spaced selected portions on a work piece of this type it is necessary that the work be not only properly radially positioned, but also axially located so that the grindings will take place at exactly the proper point in each instance. This is accomplished as shown in Figure 4 by the provision of a pair of substantially U-shaped bracket members 62 and 63 which are also suitably adjustably secured to the units 36 as by fasteners 64. The lateral flanges 62 and 63 of these bracket members serve to supplement the action of the notches in the elevating sleeves 39 so far as lateral positioning of the work is concerned, as it is moved into or out of the throat, while at thc same time the end walls have a terminal engagement with the Work pieces 50 to insure its proper end- Wise position. This may be constantly effected during the grinding operation by providing one of the members, such as 62, with an end thrust block, such .as 55, suitably mounted on antifriction thrust bearings 66. As opposed to this, the member 63 is provided with a resilient guide plate 61 which may engage the work during its descent in the guide troughs and may be projected as ,l shown in Figure 4 as a permanent resilient end sembiy including a main supporting housing 89 and an associated driving motor 10. l

Journaled within the housing is the drive sleeve 1| `bearing the sprocket 12 driven from motor 10 as by the drive chain 13. Slidable within and keyed to the sleeve 1| is the work driver 1l, having at its outer end the head 15 provided with drive pins 16, laterally received in apertures 11 of the oating clutch head 19, said pins being provided witlrthe resiliently pressed washer 19 for yieldingly holding the parts together. The clutch head 18 is oi cylindrical form and provided with the clutch jaws 80 adapted to be brought into clamping engagement with the end of the work piece by outward movement of the hydraulically actuated piston 0| contained within the head. This piston isf-further provided with a yieldlngly held washer 92 urgeable into clamping and spring compressing relation with the end ofthe work piece by movement of the piston. Accordingly, when hydraulic pressure is introduced into the rear of the floating head this pressure -will seat 4the washer against the end of the work piece and further movement will compress the spring, bringing the jaws 90 into clamping engagement therewith while conversely, upon release of this pressure, expansion oi' the spring will move the piston into the head and at the same time yrelease the pressure of the clamps.

In view of the i'act that the work piece' must be radially shifted into and out of operative position in a machine, `it will be understood that itv is necessary that the driving head just described have an axial movement as an entirety to engage V and disengage the terminal portion of the work piece. 'I'his is accomplished by providing within the housing 99 a cylinder portion 99 lin which is slideably mounted thev piston 94 coupled with sleeve 14 whereby introduction of pressure into the right hand end or the cylinder will shift the piston, and thus the head, to the left so that the parts will keep the relation illustrated in Figure 5, while introduction of pressure into the opposite side of the piston will retract the parts.

Hydraulic control mechanism It is to be noted that the actual operation of the work positioning mechanism and of the enlgagement and disengagement of the work driving iluid circuit. 'I'he circuit diagram of the controls and manner of operation will be particularly understood by reference to Figures 9 and 10. By

reference to these it will be noted that there has been provided a suitable `iluid reservoir as at 95 from which the nuid may be distributed under pressure as by pump 09 having a pressure line leading to port 91 of valve cylinder 09 containing a spool valvef99 alternatively actuable as by the' manually shiitable control lever or solenoid 9|.

Considering the work cycle as starting when a work piece has been deposited in the notches 40 with the members 99 in elevated position, a starting lever 90 is ymoved to the-position shown in Figure 9. 'I'he pressure iluid is then coupled by line 92 with the left hand end of cylinder, causing piston movement to the right so that the work is deposited in the machine as indicated in connection with Figure 3. At the same time ,the left hand end of thecylinder is connected through line 99 to the reservoir return lead 90. As the member 99 reaches its lower-most position it-trips switch |29 of the electrical control circuit which. as described, energiles solenoid 90,

moving the clamp control valve 91 to the left, coupling pressure line 91 with the pilot line 98 introducing pressure against the right hand end of valve 99, shifting same to the lei't. As valve 99 initially moves to the left it places pressure line |00 in communication with line |0|, .leading to the right hand end of work rotation control cylinv ance of valve I, allowing the pressure to flow into line |05 which, as shown, is coupled by pipe |08 with rotary coupling |01 with a tube or conduit |09 leading into the cylinder 9| back of the work clamp piston. Accordingly, this piston will be actuated for clamping of the work only after the xture, as an entirety, has been moved into telescoping relation with the work terminus.

Conversely, at the completion of the grinding operation when the solenoid 99 is de-energized, as will be subsequently described in connection with the electric diagram, spring |09 shifts valve 91 to the position shown in Figure 10, whereupon line 90 is connected to 'reservoir while the trapped pressure existing at the opposite end will cause a shifting of valve 99 to the right, in turn, coupling pressure line |0| to reservoir when the pressure through line |00 will be exerted through |01' against the left hand side of piston 84, moving same to the right and retracting the driving device out of thepath of removal of the work piece. It is to be understood that the circumferential cannelure of the bushing for valve 91 affords a permanent pressure connection between lines 91 and |00 while the movement of valve 914determines whether pressure line 91 or existing' connection 9| will be effective as respects the pilot line circuit 99.

It is to be noted that the pressure drop eiective in line |05 by shifting of valve 99 releases the clamping effect of piston4 9| prior to the application of pressure to retract the device as an entirety, and therefore. a proper sequence of telescoping of the parts. gripping of the work and subsequent release and retraction is automatically'efiected in a simple and eilicient manner.

iThe electrical control systemv Thisportion of the control of the several movements of the machine is particularly illustrated in Figure 11 in which there has been shown a two wire system comprising the leads ||0 and III, supplying current for operation of the infeed motors I2 and ||9 effecting rotation of cams I Il and ||5 for oscillating.u the respective grinding wheel carriages about their trunnions to eiect the proper approach and recession of the grinding 1 wheels with respect to the work pieces. 'Ic distinguish from their diagrammaticshowing in Figure 11 the actual cam element has been indicated in Figure 8 by the numeral IIS. vIt will be notedl -mcnt of the core or armature '|22 and thus the f switch members to the right, as viewed in Figure 11.

Energization of the switch solenoid |2| is preferably controlled by a spring opened switch |23 projecting into the path of abutment lug |24 on `the work elevator or transfer mechanism 38. Asthe elevating device is moved into its lowermost position, as indicated in Figure 3, so that the work rests 'in proper position on the work rest and against the regulating wheel, the switch |23 is closed as indicated in the diagrammatic View. This completes a control circuit from line ||0 by way of'switch |23, solenoid |2|, lead |25, normally closed switch |26 and lead |21 to main line Upon rotation of the infeed motors the rear portions of the two pivoted grinding wheel carriages will be elevated, raising the switch control cams |28, |29, |30 and |3|. In depressed position cams |28 and |30 hold in open position the switch devices |32 and |33, and as the cams rise they permit these switch members to engage vrespectively contacts |34 and |35, completing the branch circuits |36 'and |3'| for motors ||2 and ||3 respectively, so that these motors will then continue to function irrespective .of the conditioning of such members ||8| I9.

At the same time that the circuits |32- |34 and |33|35 have been completed, corresponding movement of the cam devices |29 and |3| permit of movement of the switch members |38 and |39 which are disposed in series one with the other and serve jointly to complete the circuit through lead |40 having branches, one including the switch solenoid |4| and the other the switch terminals |42. When the circuit |40 is completed, it serves to energize switch solenoid `|4| moving the multiple switch device |43 to break the circuit connection at |26 and complete the normally open switch circuits 42 and |44.

Opening of switch |26 serves to de-energize solenoid |2l, opening switches ||8 and 9; closing of switch |42 completes an alternative circuit through solenoid |4| for maintaining same subsequently energized irrespective of the position of contacts |38 and |39; while closing of switch |44 conditions circuit |45 from lead ||0 through switch solenoid |46 to contact |41.

The circuit remains conditioned as just de- I scribed until after completion of the grinding operation. During the reverse or downward swinging movement of the grinding wheel supports 23, cams |29 and |3| will move downwardly as viewed in Figure 11, reacting against the switch members |38 and |39, moving them toward the right to open the series circuit through line |40. Due, however, to the fact that switch |42 is closed, this however, has no elect on solenoid 4| which was initially energized by the closing of this series circuit. Further movement of the members |38 and |39 under the iniiuence of their respective cams serves to complete circuit |45 serially throughwontacts |41 and |49, energizing solenoid switch |46. This closes the double pole switch ISI-|52 of solenoid 9| which is coupled with spool valve 89 as previously described. En- Y in any way'effecting the hydraulic actuation oftv'. the elevating mechanism, which will continue unf til the fixture has reached its upper limit ofrnovedrive, previously described and particularly i1lus.

trated in connection with Figure 5, is employed.

In the latter event the solenoid 96 is coupled by the leads |54| 55 to the leads |40 and switch |38 in parallel with the solenoid switch |4|. Consequently, this switch will be closed, moving the hydraulic work rotation clamp control valve to the left, causing proper grasping and actuation of the work as hitherto described and maintaining this condition during the entire inward and partial outward movement o1 the grinding wheel. It is to be noted, however, that the action of the cams |29|3| on their return movement break the circuit including the coil 96 so that the work will be unclar'nped and the driving chuck withdrawn an appreciable period in advance of the actuation of solenoid 9|, reversing the effect of the carrier so that the entire device will operate in proper synchronism.

What is claimed is:

1. The combination with a machine of the centerless grinder type including a grinding wheel, a regulating wheel and an interposed work rest, of means, for controlling the operative positioning of work in the throatthus formed, including an elevating mechanism igeciprocable transversely of the throat for receiving work in elevated position as respects the throat and moving same downward into position on the workrest, means adjacent the work rest for reslliently urging the work into engagement with theregulating wheel, and means on the elevating mechanism for controlling the movement of said work engaging means into and out of operative position.l

2. The combination with a machine of the centerless grinder type including a grinding wheel, a regulating wheel and an interposed work rest, of means for controlling the operative positioning of work in the throat thus formed, including an elevating mechanism reciprocable transversely of the throat for receiving Work in elevated position as respects the throat and moving same downward into position on the work rest, means adjacent the work rest for resiliently urging the work into engagement with the regulating wheel, means on the elevating mechanism for controlling the movement of said work engaging means into and out of operative position, and means operable on descent of the elevating mechanism for initiating the grinding operation.

3. The combination with a grinding machine including a vbed or support, a pair of spaced regulating wheels mounted thereon for rotation about parallel axes, a pair of shiftable grinding wheel supports, grinding wheels carried by said wheel supports in opposition to the respective regulating wheels, an elevating mechanismvfor controlling presentation of a workpiece in opposition for grinding of selected portions thereof by the respective grinding Wheels, and means actuable by movement of .the work elevating mechanism for effecting individual movement of the respective grinding Wheels in the direction of the work.

4. The combination with a grinding machine including a bed or support, a pair of spaced regulating wheels mounted thereon for rotation about y ananas Y parallel axes, a pair of shiftable grinding wheel supports, grinding wheels'carried by said wheel.

supports in opposition to the respective regulating wheels, an elevating mechanism for controlling presentation of a work piece in opposition for grinding of selected portions thereof by the respective grinding wheels, meansl actuable by movement of the work elevating mechanism for effecting individual movement of the respective grinding wheels in the direction of the work, and

means actuable by retraction of the grinding vwheels for determining the operation of the controlling presentation of a work piece inopposition for grinding of selected portions thereof by the respective grinding wheels, means actuable by movement of the work elevating mechanism for effecting individual movement of the respective grinding wheels in the direction of the work, and means actuable by retraction of the grinding wheels for determining the operation of the elevating mechanism for removal ofthe work from grinding position, said means including serially arranged control devices individual to the respective grinding wheel units whereby. work retraction is delayed luntil all grinding wheel units are in retracted position.

6. A machine of-the character described, including a pair of spaced work supporting members, regulating wheels individual to the Support* ing members disposed at one side thereof and grinding wheel units individual to each of said members disposed at the opposite side thereof, whereby spaced aligned work receiving throats are provided, a pair of work elevating mechanisms, each individual to one of said work supports, and a hydraulically operated mechanism for eiecting synchronous movement of the elevating mechanisms whereby a massive' elongated work piece may be satisfactorily positioned for simultaneous grinding of spaced selected portions thereof by the respective grinding wheels.

'7. A machine of the character described, including a pair of spaced work supporting 'members, regulating wheels individual to the supporting members disposed at one side thereof and grinding wheel units individuen` to each cfsaid' members disposed at the opposite side thereof,

whereby spaced aligned work receiving throats are provided, a pair of work elevating 'mechanisms, each individual to one of said work supports, a hydraulically operated mechanism for effecting synchronous movement of the elevating mechanisms whereby a massive elongated work piece may be satisfactorily positioned for simultaneous grinding of spaced selected portions thereof by the respective grinding wheels, and guide members exteriorly disposed as respects the grinding units having portions for terminally engaging opposite ends of the work piece for determining the axial positioning thereof.

8. A machine of the character described,inclu.d l

ing a pair of spaced work supporting members, regulating wheels individual to the supporting members disposed at one side thereof and grinding wheel units individual to each of saidmembers disposed at the opposite side thereof, whereby unidirectional movementof the elevating mechdevice with the-work.

spaced aligned work receiving threats ere previded, a pair of work elevating mechanisms, each individual to one of 'said work supports, a hydraulically operated mechanism for effecting t synchronous movement of the elevating mech- 5 anisms whereby a massive elongated work piece may be satisfactorilyl positioned for simultaneous grinding of spaced selected portions thereof by the respective grinding.. wheels, means for yield-l ingly urging the work in a'direction toward the regulating wheel. and means on the elevating mechanismfor eifecting successive toward and from movements of said urging means during anism.

9. The -combinationnwith-a machine of the lcenterless grinder type including opposed grinding and regulating wheels'4 and interposed work rest forming a three-point 'contact grinding throat, of means for facilitating grinding of heavy work pieces withinthe throat, said means including an elevating mechanism disposed adjacent the throat for lateral engagement with a work piece, auxiliary driving mechanism disposed adjacent the throat and movable into position for terminally engagingthe. work piece, and means operable by movement of the elevating device for effecting operative engagement of the driving 10. The combination with a machine of the centerless grinder type including opposed grinding and regulating wheels and interposed work rest forming a' three-point contact grinding throat, of means for facilitating grinding of heavy work pieces within the throat, said means includ- :i ing an elevating mechanism disposed adjacent the throat for lateral engagement with a work piece, auxiliary driving mechanism disposed adjacent the throat and movable into position for terminally engaging the work piece, means operable by P movement of the elevating device for effecting operative engagement of the driving device with 'the workwand interlocking controls for succesrsively effecting retraction of the work driving mechanism and actuation of the elevating device to remove the work from the grinding throat. 11, The combination with a machine of the centerless grinder type including opposed grinding and regulating wheels and interposed work rest forming a three-point contact grinding throat,

-of means for facilitating grinding of heavy work pieces within the throat. said means including an elevating mechanism disposed adjacent the throat forlateral engagement with a workpiece,

'auxiliary driving mechanism disposed adjacent 55 the throat and movable into position for terminally' engaging the work piece, means operable by movement of the elevating device for effecting operative engagement of the driving device with the work', interlocking controls for'successiveiy 00 effecting retraction of the work driving mechanism and actuation of the elevating device to remove the work from the grinding throat, and means for eifectingy a restriction and expansion of the grinding throat, and an actuator for the g5 controls operative on expansion of the grinding throat for effecting the release and removal of a work piece.

` 12. A machine for effecting rotary presentation of a work piece to a grinding wheel including a friction drive wheel for engagement with the 2 periphery of the work piece, a first hydraulically controlled mechanism for moving the work piece into engagement with saidfriction wheel, a rst control device for determining the movement of u said hydraulically controlled mechanism, a second drive device movable into telescoping relationship with the terminal portion of the work piece, hydraulically operable means for moving said drive device, and means operable by movement of the first hydraulically actuated device for controlling the subsequent actuation of said hydraulically 0perable means for moving the second drive device.

13. A machine for effecting rotary presentation of a work piece lto a grinding wheel including a friction drive wheel for engagement with the periphery of the Work piece, a first hydraulically controlled mechanism for moving the work piece into engagement with said friction Wheel, a first control devicevfor determining the movement of said hydraulically controlled mechanism, a second drive device movable into telescoping relationship with the terminal portion of the work piece, hydraulically operable means for moving said drive device, means operable by movement of the rst hydraulically actuated device for controlling the subsequent actuation of said hydraulically operable means for moving the second drive device, said second drive device including a main unit and a portion movable with and relative to the main unit, and a timing device for'eiecting said relative movement subsequent to the movement of the unit as an entirety.

14. A machine for effecting rotary presentation of a work piece to a grinding wheel including a friction drive wheel for engagement With the periphery of the work piece, a. first hydraulically controlled mechanism for moving the Work piece into engagement with said friction wheel, a first controldevice for determining the movement of said hydraulically controlled mechanism, a second drive device movable into telescoping relationship with the terminal portion of the work piece, hy-

draulically operable means for moving said device, means operable by movementl of the rst hydraulically actuated device for controlling the subsequent actuation of said hydraulically operable means for moving the second drive device, said second drive device including a main unit and a portion movable with and relative to the main unit, a timing device for effecting said relative movement subsequent to the movement of the unit as an entirety, and an additional delayed motion mechanism for effecting corresponding movements of said last mentioned parts in reverse order.

.15. A machine of the character described including rotary Work supporting members, a grinding wheel movable in a direction toward and from s'aid rotary Work supporting members for effecting the grinding operation on a work piece supported thereby, a Work transfer mechanism shiftable to present .a work piece into or out of engagement With said rotary work supporting members, means for effecting in and out movement of the grind-v ing Wheel, anda control mechanism for said parts including a first actuator operable by movement of the Work transfer mechanism for initiating' 

